1. Field of the Invention
The present invention generally relates to a vehicle cabin heating system. More specifically, the present invention relates to supplying heating a vehicle cabin interior space using at least one infrared heater.
2. Background Information
For many years, automotive vehicles have been provided with climate control systems (e.g., heating, ventilating and air conditioning (HVAC) systems) in order to provide a more comfortable environment for the driver and any passengers. Typically, fresh air is supplied to the HVAC system via a ductwork extending from a cowl box of the vehicle to cabin outlets in the vehicle cabin interior space. The conventional approach to heat the vehicle cabin is to utilize waste heat from the power-train system by powering a blower motor and delivering air through a heat exchanger that uses circulating engine coolant. In particular, in such a conventional engine coolant based heating system, a heater core (heat exchanger) is disposed in the ductwork between the cowl box and the cabin outlets, and a blower is provided in the ductwork to deliver the heated air to the cabin. The heater core is normally heated by the engine coolant from the vehicle's engine. In cold conditions, when the vehicle is first started, the engine is cold. In other words, there may not be significant temperature potential available to quickly warm the cabin with this conventional engine coolant based heating system, the occupants must wait to be comfortable. Thus, the engine coolant is also cold and is insufficient to warm the air entering the vehicle cabin. This results in a period of time in which the cabin remains below the desired cabin temperature. In order to solve this problem, an infrared heater has been proposed in U.S. Pat. No. 3,619,555 to Bassett, Jr. (assigned to General Motors Corporation), in which heater is designed to be energized only when the vehicle engine coolant is below a predetermined temperature and the ignition switch is “on”.
In recent years, hybrid vehicles and electric vehicles have become more popular. A hybrid vehicle includes an internal combustion engine and an electric motor or a battery as power sources for providing a driving force to a vehicle drive train. In the case of hybrid vehicles, the internal combustion engine is stopped, when travelling in an electric (EV) mode. When the hybrid vehicle is travelling in an electric (EV) mode, the engine coolant will typically stop being circulated through the heater core (heat exchanger) that is disposed in the HVAC ductwork. Thus, the engine coolant temperature will drop while the vehicle is travelling in an electric (EV) mode. In the above mentioned patent, the infrared heater operates when the engine coolant temperature drops below a predetermined temperature. Apparently, the infrared heater will continue to operate until the engine coolant temperature above the predetermined temperature of the coolant. Thus, the proposed heating system of the above mentioned patent is not well suited for hybrid vehicles. Likewise, the proposed heating system of the above mentioned patent is not well suited for electric vehicles. Electric vehicles often have a cooling system for the batteries and/or the motor that somewhat resembles that of an internal combustion engine configuration. However, the waste heat generation is very low compared to an internal combustion engine and as a consequence has a reduced capability to heat the cabin.
In view of the above, it will be apparent to those skilled in the art from this disclosure that there exists a need for an improved vehicle cabin heating system. This invention addresses this need in the art as well as other needs, which will become apparent to those skilled in the art from this disclosure.